The ACLU is the American Civil Liberties Union, which was run for its first 30 years by a Unitarian socialist named Roger Baldwin, who helped found it in 1920. During most his tenure at the ACLU Baldwin was sympathetic to the communist movement, only breaking off ties on the eve of World War II.
The ACLU repeatedly uses the legal system to purge Christianity from public life, so much so that conservatives refer to it as the "Anti-Christian Liberties Union." For example, the ACLU has made numerous demands and filed lawsuits to remove the Ten Commandments and Christian crosses from public places and symbols.
In Pennsylvania, the ACLU received over 1 million dollars in legal fees for obtaining a court order to prohibit a school district from making a brief statement alerting students to the theory of intelligent design as an alternative to evolution.